Block copolymers including high vinyl segments

ABSTRACT

A method for the preparation of block copolymers including at least one high vinyl segment, the method comprising (i) charging into a reactor a diene monomer in a hydrocarbon solvent, a catalytically effective amount of anionic initiator, and an oligomeric oxolanyl propane, whereby the reactor is optionally cooled; (ii) allowing the diene monomer to polymerize at a peak polymerization temperature of at least about 18° C. and less than about 60° C. to form a first block where the vinyl content is at least about 50 percent by weight; (iii) after step (ii), charging into the reactor a vinyl aromatic monomer, whereby the reactor is optionally heated to a temperature up to about 60° C.; (iv) allowing the vinyl aromatic monomer to polymerize to form a second block; and (v) optionally charging into the reactor a quenching agent.

This application is a continuation application of U.S. Non-Provisionalapplication Ser. No. 14/330,468, filed on Jul. 14, 2014, which is acontinuation application of U.S. Non-Provisional application Ser. No.12/508,296, filed on Jul. 23, 2009, each of which claims the benefit ofU.S. Provisional Application Ser. No. 61/083,305 filed on Jul. 24, 2008,all of which are incorporated herein by reference.

FIELD OF THE INVENTION

One or more embodiments of the present invention are directed towardmethods of preparing block copolymers that include at least onepolyvinyl aromatic segment and at least one polydiene segment, where thepolydiene segment is characterized by a relatively high vinyl content.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a method forthe preparation of block copolymers including at least one high vinylsegment, the method comprising (i) charging into a reactor a dienemonomer in a hydrocarbon solvent, a catalytically effective amount ofanionic initiator, and an oligomeric oxolanyl propane, whereby thereactor is optionally cooled; (ii) allowing the diene monomer topolymerize at a peak polymerization temperature of at least about 18° C.and less than about 60° C. to form a first block where the vinyl contentis at least about 50 percent by weight; (iii) after step (ii), charginginto the reactor a vinyl aromatic monomer, whereby the reactor isoptionally heated to a temperature up to about 60° C.; (iv) allowing thevinyl aromatic monomer to polymerize to form a second block; and (v)optionally charging into the reactor a quenching agent.

One or more embodiments of the present invention provide a method forthe preparation of block copolymers including at least one high vinylsegment, the method comprising (i) charging into a reactor a dienemonomer in a hydrocarbon solvent, a catalytically effective amount ofanionic initiator, and an oligomeric oxolanyl propane, whereby thereactor is optionally cooled; (ii) allowing the diene monomer topolymerize at a peak polymerization temperature of at least about 18° C.and less than about 60° C. to form a first block where the vinyl contentis at least about 50 percent by weight; (iii) after step (ii), charginginto the reactor a vinyl aromatic monomer; (iv) allowing the vinylaromatic monomer to polymerize to form a second block; (v) after step(iv), charging into the reactor diene monomer; (vi) allowing the monomerto polymerize at a peak polymerization temperature up of at least about18° C. and less than about 60° C. to form a third block where the vinylcontent is at least about 50 percent by weight; (vii) optionally furthercharging into the reactor the vinyl aromatic monomer and allowing thevinyl aromatic monomer to polymerize to form a fourth block; and (viii)optionally charging into the reactor a quenching agent.

One or more embodiments of the present invention provide a blockcopolymer defined by the formula I: α-V-D-ω, where V is a polyvinylaromatic block, D is a polydiene block, α and ω are each independently ahydrogen atom, a functional group, or a polymeric segment or block, andwhere D is characterized by a vinyl content of at least 50%.

Other embodiments provide a block copolymer defined by the formula II:d-V-D-ω, where d is a polydiene block deriving from the polymerizationof diene monomer, V, D, and ω are as defined above with respect toformula I, and where D and d are characterized by a vinyl content of atleast 50%.

Other embodiments provide a block copolymer defined by the formula III:α-V^(O)-D-V′-ω, where each V is independently a polyvinyl aromaticblock, D is a polydiene block, α and ω are each independently a hydrogenatom, a functional group, or a polymeric segment or block, and where Dis characterized by a vinyl content of at least 50%.

Other embodiments provide a block copolymer defined by the formula IV:d-V^(O)-D-V′-ω, where d is a polydiene block, and V^(O), V′, D, and ωare as defined above with respect to Formula III, and where D and d arecharacterized by a vinyl content of at least 50%.

Other embodiments provide a method for preparing a block copolymer ofthe type including at least one diene block and at least one vinylaromatic block, where the block copolymer is prepared in solvent usinganionic polymerization techniques, wherein the improvement comprisessynthesizing the at least one diene block in the presence of at leastabout 0.025 pbw oligomeric oxolanyl propane per 100 pbw monomer andmaintaining the peak polymerization temperature at a temperature of atleast about 18° C. and less than about 60° C.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

One or more embodiments of the present invention relate to blockcopolymers including at least one polyvinyl aromatic block and at leastone polydiene block. The polydiene block is characterized by arelatively high vinyl content. In one or more embodiments, where thecopolymer includes multiple diene blocks, the overall copolymer ischaracterized by an advantageously high vinyl content.

One or more embodiments of the present invention provide blockcopolymers that may be defined by the formula I:α-V-D-ωwhere V is a polyvinyl aromatic block, D is a polydiene block, α and ωare each independently a hydrogen atom, a functional group, or apolymeric segment or block, and where D is characterized by a vinylcontent of at least 50%.

In one or more embodiments, polyvinyl aromatic blocks include three ormore mer units deriving from the polymerization of vinyl aromaticmonomer. Exemplary vinyl aromatic monomer include, without limitation,styrene, α-methyl styrene, p-methylstyrene, and vinylnaphthalene. In oneor more embodiments, polydiene blocks include three or more mer unitsderiving from the polymerization of conjugated diene monomer. Exemplaryconjugated diene monomer include, without limitation, 1,3-butadiene,isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene,2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene. In one or more embodiments,functional groups include organic or inorganic moieties that include atleast one heteroatom. In one or more embodiments, polymeric segmentsinclude homopolymers or copolymers.

In one or more embodiments, D of formula I is characterized by a vinylcontent (i.e. the percentage of mer units positioned in the1,2-microstructure) of at least 50%, in other embodiments at least 55%,in other embodiments at least 60%, in other embodiments at least 65%, inother embodiments at least 70%, in other embodiments at least 75%, inother embodiments at least 80%, and in other embodiments at least 85%.In these or other embodiments, D of formula I is characterized by avinyl content of less than 100%, in other embodiments less than 95%, inother embodiments less than 90%, in other embodiments less than 85%, andin other embodiments less than 80%. The vinyl content may be determinedby proton NMR, and as reported herein refers to the percentage of merunits positioned in the 1,2-microstructure based on the total mer unitsderiving from the polymerization of conjugated diene monomer.

In one or more embodiments, the D block of formula I includes at least250, in other embodiments at least 350, in other embodiments at least450, and in other embodiments at least 550 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, the D block of formula I includes less than 800, in otherembodiments less than 750, in other embodiments less than 700, in otherembodiments less than 650, and in other embodiments less than 600 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the V block copolymer of formula I includesat least 50, in other embodiments at least 120, in other embodiments atleast 145, in other embodiments at least 160, in other embodiments atleast 180, in other embodiments at least 200, and in other embodimentsat least 225 mer units deriving from the polymerization of vinylaromatic monomer. In these or other embodiments, the V block of formulaI includes less than 400, in other embodiments less than 350, in otherembodiments less than 325, in other embodiments less than 300, and inother embodiments less than 280 mer units deriving from thepolymerization of vinyl aromatic monomer.

In one or more embodiments, the block copolymers defined by the formulaI are characterized by low levels of tapering, which may also bereferred to as randomness between the blocks of the polymer chain. Inother words, and for example, a vinyl aromatic block (e.g. polystyreneblock) of the block copolymer will have a limited number, if any, of merunits deriving from conjugated diene (e.g. 1,3-butadiene) within theblock. For purposes of this specification, tapering will refer to thelevel or amount of mer units (in moles) present within a given block asan impurity in that block (e.g. styrene mer units within a polybutadieneblock). In one or more embodiments, the blocks of the block copolymersdefined by the formula I include less than 5%, in other embodiments lessthan 3%, in other embodiments less than 1%, and in other embodimentsless than 0.5% tapering in any given block of the block copolymer. Inthese or other embodiments, the blocks of the block copolymers definedby the formula I are substantially devoid of tapering, which includesthat amount of tapering or less that will not have an appreciable impacton the block copolymer. In one or more embodiments, the blocks of theblock copolymers defined by the formula I are devoid of tapering.

In one or more embodiments, a is a diene block deriving from thepolymerization of diene monomer, and therefore the block copolymer canbe defined by the formula IId-V-D-ωwhere d is a polydiene block deriving from the polymerization of dienemonomer, V, D, and ω are as defined above with respect to formula I, andwhere D and d are characterized by a vinyl content of at least 50%.

In one or more embodiments, d of formula II is characterized by a vinylcontent (i.e. the percentage of mer units positioned in the1,2-microstructure) of at least 50% in other embodiments at least 55%,in other embodiments at least 60%, in other embodiments at least 65%, inother embodiments at least 70%, in other embodiments at least 75%, inother embodiments at least 80%, and in other embodiments at least 85%.In these or other embodiments, D is characterized by a vinyl content ofless than 100%, in other embodiments less than 95%, in other embodimentsless than 90%, in other embodiments less than 85%, and in otherembodiments less than 80%.

In one or more embodiments, d of formula II includes at least 10, inother embodiments at least 40, in other embodiments at least 60, and inother embodiments at least 80, in other embodiments at least 100, and inother embodiments at least 120 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, d of formula II includes less than 500, in otherembodiments less than 350, in other embodiments less than 250, in otherembodiments less than 200, in other embodiments less than 180, in otherembodiments less than 160, and in other embodiments less than 120 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the blocks of the block copolymers definedby the formula II include less than 5%, in other embodiments less than3%, in other embodiments less than 1%, and in other embodiments lessthan 0.5% tapering in any given block of the block copolymer. In theseor other embodiments, the blocks of the block copolymers defined by theformula II are substantially devoid of tapering, which includes thatamount of tapering or less that will not have an appreciable impact onthe block copolymer. In one or more embodiments, the blocks of the blockcopolymers defined by the formula II are devoid of tapering.

One or more embodiments of the present invention provide blockcopolymers that may be defined by the formula IIIα-V^(O)-D-V′-ωwhere each V is independently a polyvinyl aromatic block, D is apolydiene block, α and ω are each independently a hydrogen atom, afunctional group, or a polymeric segment or block, and where D ischaracterized by a vinyl content of at least 50%.

In one or more embodiments, D of formula III is characterized by a vinylcontent (i.e. the percentage of mer units positioned in the1,2-microstructure) of at least 50% in other embodiments at least 55%,in other embodiments at least 60%, in other embodiments at least 65%, inother embodiments at least 70%, in other embodiments at least 75%, inother embodiments at least 80%, and in other embodiments at least 85%.In these or other embodiments, D is characterized by a vinyl content ofless than 100%, in other embodiments less than 95%, in other embodimentsless than 90%, in other embodiments less than 85%, and in otherembodiments less than 80%.

In one or more embodiments, the D of formula III includes at least 250,in other embodiments at least 350, in other embodiments at least 450,and in other embodiments at least 550 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, the D block of formula III includes less than 800, in otherembodiments less than 750, in other embodiments less than 700, in otherembodiments less than 650, and in other embodiments less than 600 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the V^(O) and V′ blocks of formula III eachindependently include at least 25, in other embodiments at least 60, inother embodiments at least 75, in other embodiments at least 80, inother embodiments at least 90, in other embodiments at least 100, and inother embodiments at least 115 mer units deriving from thepolymerization of vinyl aromatic monomer. In these or other embodiments,V^(O) and V′ each independently include less than 200, in otherembodiments less than 175, in other embodiments less than 160, in otherembodiments less than 150, and in other embodiments less than 140 merunits deriving from the polymerization of vinyl aromatic monomer.

In one or more embodiments, the ratio of V^(O) mer units to V′ mer unitsis at least 0.2:1, in other embodiments at least 0.4:1, in otherembodiments at least 0.6:1, in other embodiments 0.8:1, in otherembodiments at least 0.9:1, and in other embodiments at least 0.95:1. Inthese or other embodiments, the ratio of V^(O) mer units to V′ mer unitsis less than 4:1, in other embodiments less than 3:1, in otherembodiments less than 2:1, in other embodiments less than 1.5:1, inother embodiments less than 1.1:1, and in other embodiments less than1.05:1. In one or more embodiments, the ratio of V^(O) mer units to V′mer units is about 1:1.

In one or more embodiments, the blocks of the block copolymers definedby the formula III include less than 5%, in other embodiments less than3%, in other embodiments less than 1%, and in other embodiments lessthan 0.5% tapering in any given block of the block copolymer. In theseor other embodiments, the blocks of the block copolymers defined by theformula III are substantially devoid of tapering, which includes thatamount of tapering or less that will not have an appreciable impact onthe block copolymer. In one or more embodiments, the blocks of the blockcopolymers defined by the formula III are devoid of tapering.

In one or more embodiments, α of formula III is a diene block, andtherefore the block copolymer can be defined by the formula IVd-V^(O)-D-V′-ωwhere d is a polydiene block, V^(O), V′, D, and ω are as defined abovewith respect to Formula III, and where D and d are characterized by avinyl content of at least 50%.

In one or more embodiments, d of formula IV is characterized by a vinylcontent (i.e. the percentage of mer units positioned in the1,2-microstructure) of at least 50%, in other embodiments at least 55%,in other embodiments at least 60%, in other embodiments at least 65%, inother embodiments at least 70%, in other embodiments at least 75%, inother embodiments at least 80%, and in other embodiments at least 85%.In these or other embodiments, d of formula IV is characterized by avinyl content of less than 100%, in other embodiments less than 95%, inother embodiments less than 90%, in other embodiments less than 85%, andin other embodiments less than 80%.

In one or more embodiments, d of formula IV includes at least 10, inother embodiments at least 40, in other embodiments at least 60, and inother embodiments at least 80, in other embodiments at least 100, and inother embodiments at least 120 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, d of formula IV includes less than 500, in otherembodiments less than 350, in other embodiments less than 250, in otherembodiments less than 200, in other embodiments less than 180, in otherembodiments less than 160, and in other embodiments less than 120 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the overall vinyl content of the blockcopolymers of the present invention may be at least 50%, in otherembodiments at least 55%, in other embodiments at least 60%, in otherembodiments at least 65%, in other embodiments at least 70%, in otherembodiments at least 75%, in other embodiments at least 80%, and inother embodiments at least 85%. In these or other embodiments, d offormula IV is characterized by a vinyl content of less than 100%, inother embodiments less than 95%, in other embodiments less than 90%, inother embodiments less than 85%, and in other embodiments less than 80%.As those skilled in the art will appreciate, the overall vinyl contentof the block copolymers can be tailored by adjusting the vinyl contentof particular diene blocks. For example, where the block copolymers aredefined by the formulae II and IV, the vinyl content of the d block canbe increased, without necessarily providing a corresponding increase tothe D block, to affect an overall increase in the vinyl content of blockcopolymer.

In one or more embodiments, the blocks of the block copolymers definedby the formula IV include less than 5%, in other embodiments less than3%, in other embodiments less than 1%, and in other embodiments lessthan 0.5% tapering in any given block of the block copolymer. In theseor other embodiments, the blocks of the block copolymers defined by theformula IV are substantially devoid of tapering, which includes thatamount of tapering or less that will not have an appreciable impact onthe block copolymer. In one or more embodiments, the blocks of the blockcopolymers defined by the formula IV are devoid of tapering.

In one or more embodiments, the peak molecular weight (Mp) of theoverall block copolymers employed in the present invention may be atleast 40 kg/mole, in other embodiments at least 50 kg/mole, in otherembodiments at least 60 kg/mole, and in other embodiments at least 70kg/mole. In these or other embodiments, the overall peak molecularweight of the block copolymers of the present invention may be less than150 kg/mole, in other embodiments less than 125 kg/mole, in otherembodiments less than 100 kg/mole, and in other embodiments less than 90kg/mole.

In one or more embodiments, the block copolymers employed in the presentinvention can be synthesized by employing anionic polymerizationtechniques. In one or more embodiments, living polymers includeanionically polymerized polymers (i.e., polymers prepared by anionicpolymerization techniques). Anionically-polymerized living polymers maybe formed by reacting anionic initiators with certain unsaturatedmonomers to propagate a polymeric structure. Throughout formation andpropagation of the polymer, the polymeric structure may be anionic or“living.” A new batch of monomer subsequently added to the reaction canadd to the living ends of the existing chains and increase the degree ofpolymerization. A living polymer, therefore, includes a polymericsegment having a living or reactive end. Anionic polymerization isfurther described in George Odian, Principles of Polymerization, ch. 5(3^(rd) Ed. 1991), or Panek, 94 J. Am. Chem. Soc., 8768 (1972), whichare incorporated herein by reference.

In one or more embodiments, the block copolymers of the presentinvention can be prepared by sequential addition of the distinct monomerthat give rise to the various blocks. For example, vinyl aromaticmonomer can be charged and polymerized to form a living polyvinylaromatic living polymer chain. After the vinyl aromatic monomer isconsumed or substantially consumed, the conjugated diene monomer can becharged. The conjugated diene monomer adds to the living polyvinylaromatic chain and forms a polydiene block tethered thereto. After thediene monomer is consumed or substantially consumed, additional monomercan be added to form another block tethered to the copolymer. Forexample, vinyl aromatic monomer can be charged to form another vinylaromatic block. This process can be continued until the living polymeris quenched (e.g. protonated).

The process can be started by employing an anionic polymerizationinitiator, although as those skilled in the art appreciate, other meanscan be employed to initiate the polymerization. Exemplary anionicinitiators include organolithium compounds. In one or more embodiments,organolithium compounds may include heteroatoms. In these or otherembodiments, organolithium compounds may include one or moreheterocyclic groups.

Types of organolithium compounds that may be used as initiators include,but are not limited to, alkyllithium, aryllithium compounds, andcycloalkyllithium compounds. Specific examples of organolithiumcompounds include ethyllithium, n-propyllithium, isopropyllithium,n-butyllithium, sec-butyllithium, t-butyllithium, n-amyllithium,isoamyllithium, and phenyllithium. Still other anionic initiatorsinclude organosodium compounds such as phenylsodium and2,4,6-trimethylphenylsodium. Also contemplated are those anionicinitiators that give rise to di-living polymers, wherein both ends of apolymer chain is living. Examples of such initiators include dilithioinitiators such as those prepared by reacting 1,3-diisopropenylbenzenewith sec-butyllithium. These and related difunctional initiators aredisclosed in U.S. Pat. No. 3,652,516, which is incorporated herein byreference.

In particular embodiments, the organolithium compounds include a cyclicamine-containing compound such as lithiohexamethyleneimine. These andrelated useful initiators are disclosed in the U.S. Pat. Nos. 5,332,810,5,329,005, 5,578,542, 5,393,721, 5,698,646, 5,491,230, 5,521,309,5,496,940, 5,574,109, and 5,786,441, which are incorporated herein byreference. In other embodiments, the organolithium compounds includealkylthioacetals (e.g., dithianes) such as2-lithio-2-methyl-1,3-dithiane. These and related useful initiators aredisclosed in U.S. Pat. No. 7,153,919, and U.S. Publ. Nos. 2006/0264590,and 2006/0264589, which are incorporated herein by reference. In stillother embodiments, the organolithium compounds includealkoxysilyl-containing initiators, such as lithiatedt-butyldimethylpropoxysilane. These and related useful initiators aredisclosed in U.S. Pat. No. 7,335,712, which is incorporated herein byreference. In one or more embodiments, the anionic initiator employed istrialkyltinlithium compound such as tri-n-butyltinlithium. These andrelated useful initiators are disclosed in U.S. Pat. Nos. 3,426,006 and5,268,439, which are incorporated herein by reference.

The amount of initiator employed in conducting anionic polymerizationscan vary widely based upon the desired polymer characteristics. In oneor more embodiments, from about 0.1 to about 100, and in otherembodiments from about 0.33 to about 10 mmol of lithium per 100 g ofmonomer is employed.

In one or more embodiments, synthesis of the block copolymers of thepresent invention is conduction in solution, which includes thosepolymerization mediums where the monomer to be polymerized is dissolvedin a solvent. In these or other embodiments, the polymer that issynthesized is also soluble in the solvent. In one or more embodiments,the anionic polymerizations of the present invention may be conducted ina polar solvent such as tetrahydrofuran (THF) or dialkyl ethers such asdimethyl ether, or a non-polar hydrocarbon such as the various cyclicand acyclic hexanes, heptanes, octanes, pentanes, their alkylatedderivatives, and mixtures thereof, as well as benzene. Mixtures of twoor more of these solvents can also be used. As those skilled in the artappreciate, the solvent can be selected to optimize the solubility ofthe monomer that is polymerized or the polymer that is synthesized.

In order to achieve the desired vinyl content of the polydiene blocks,polymerization of the diene monomer can be conducted in the presence ofa vinyl modifier while maintaining the polymerization medium belowcertain threshold temperatures.

In one or more embodiments, compounds useful as vinyl modifiers includethose having an oxygen or nitrogen heteroatom and a non-bonded pair ofelectrons. Examples include dialkyl ethers of mono and oligo alkyleneglycols; “crown” ethers; tertiary amines such as tetramethylethylenediamine (TMEDA); linear THF oligomers; and the like. Specific examplesof compounds useful as vinyl modifiers include tetrahydrofuran (THF),linear and cyclic oligomeric oxolanyl alkanes such as2,2-bis(2′-tetrahydrofuryl) propane, di-piperidylethane,dipiperidylmethane, hexamethylphosphoramide, N—N′-dimethylpiperazine,diazabicyclooctane, dimethyl ether, diethyl ether, tributylamine and thelike. The linear and cyclic oligomeric oxolanyl alkane modifiers aredescribed in U.S. Pat. No. 4,429,091, which is incorporated herein byreference. Blends of two or more of the above vinyl modifiers mayadvantageously be employed to achieve the properties sought by thepresent invention. In particular embodiments, it has advantageously beendiscovered that bis-oxolanyl propane and oligomers thereof, includingthose disclosed in U.S. Pat. Nos. 4,429,091, 4,647,635, 5,241,008, and5,331,035, which are incorporated herein by reference, are extremelybeneficial for practicing the present invention and advantageously allowfor production of the desired high-vinyl block copolymers undercommercially feasible rates and conditions.

The amount of vinyl modifier (e.g. bis-oxolanyl propane) employed inconducting anionic polymerizations can vary widely based upon thedesired vinyl content. In one or more embodiments, the amount of vinylmodifier employed may be expressed in parts by weight modifier per 100parts by weight monomer. In one or more embodiments, at least 0.025parts by weight, in other embodiments at least 0.1 parts by weight, inother embodiments at least 0.2 parts by weight, in other embodiments atleast 0.35 parts by weight, and in other embodiments at least 0.5 partsby weight vinyl modifier per 100 parts by weight monomer may beemployed. In these or other embodiments, less than 10 parts by weight,in other embodiments less than 5 parts by weight, in other embodimentsless than 2.5 parts by weight, in other embodiments less than 1.0 partsby weight, and in other embodiments less than 0.8 parts by weight vinylmodifier per 100 parts by weight monomer may be employed.

In other embodiments, the amount of vinyl modifier employed may beexpressed based upon the number of moles of vinyl modifier per moles oflithium (or other metal) associated with the initiator. In one or moreembodiments, at least 0.1 moles, in other embodiments at least 0.5moles, in other embodiments at least 1.0 moles, in other embodiments atleast 1.25 moles, and in other embodiments at least 1.5 moles of vinylmodifier per mole of lithium may be employed. In these or otherembodiments, less than 20 moles, in other embodiments less than 10moles, in other embodiments less than 5 moles, in other embodiments lessthan 2.5 moles, and in other embodiments less than 2.0 moles of vinylmodifier per mole of lithium may be employed.

In one or more embodiments, the polymerization of the polydiene blocks(i.e. D and d) is conducted by setting the initial batch temperature(i.e. the temperature of the polymerization medium at the beginning ofthe polymerization of diene monomer) at temperatures below 30° C., inother embodiments below 25° C., in other embodiments below 20° C., inother embodiments below 15° C., and in other embodiments below 12° C. Inthese or other embodiments, the initial batch temperature may be set atabove −10° C., in other embodiments above 0° C., and in otherembodiments above 5° C.

In one or more embodiments, the temperature of the polymerization mediumduring the polymerization of conjugated diene monomer (i.e. during theformation of the polydiene blocks D or d) is maintained so as to achievea peak polymerization temperature below 60° C., in other embodimentsbelow 55° C., in other embodiments below 50° C., in other embodimentsbelow 48° C., in other embodiments below 46° C., in other embodimentsbelow 40° C., in other embodiments below 35° C., and in otherembodiments below 30° C. As those skilled in the art appreciate, theinitial batch temperature, as well as the peak polymerizationtemperature, can be controlled by employing several techniques, as wellas combinations thereof. For example, the jacket temperature can beadjusted, reflux condensers can be employed, particular solvents can beselected, and the solids concentration of the polymerization can beadjusted. It has unexpectedly been discovered that the use ofbis-oxolanyl propane and oligomers thereof as vinyl modifiers in theproduction of the block copolymers of the present inventionadvantageously allows for peak polymerization temperatures that arerelatively high and yet achieve the benefits of relatively high vinylpolydiene blocks. As those skilled in the art will appreciate, this isextremely advantageous because it allows for the production of the blockcopolymers of the present invention at relatively high rates ofpolymerization yielding relatively high volume of polymer, which makesproduction of the block copolymers of the present invention commerciallyviable. For example, in one or more embodiments of the presentinvention, polymerization of the D block or blocks of the blockcopolymers of one or more embodiments of the present invention (e.g. thepolydiene blocks) can be allowed to achieve a peak polymerizationtemperature of at least 18° C., in other embodiments least 20° C., inother embodiments at least 23° C., in other embodiments at least 25° C.,in other embodiments at least 27° C., and in other embodiments at least30° C. In these or other embodiments, particularly where blockcopolymers of the present invention include a diene block d (such as informula II or IV), it has unexpectedly been discovered that advantagescan be achieved by maintaining lower peak polymerization temperaturesthan maintained during polymerization of the D blocks. For example, inone or more embodiments, the peak polymerization temperature achievedduring polymerization of the d block is at least at least 5° C., inother embodiments least 8° C., in other embodiments at least 10° C., inother embodiments at least 12° C., in other embodiments at least 15° C.,and in other embodiments at least 18° C. In these or other embodiments,the peak polymerization temperature achieved during polymerization ofthe d block is less than 35° C., in other embodiments less than 30° C.,in other embodiments less than 27° C., in other embodiments less than25° C., and in other embodiments less than 22° C.

In one or more embodiments, it has been unexpectedly discovered that bymaintaining the solids concentration of the polymerization medium duringformation of the polydiene blocks defined by D (in the formulae above)at particular concentrations, benefits are realized in terms of anadvantageous product produced at commercially viable rates and volumes.For example, in one or more embodiments, the solids content of thepolymerization medium during formation of the D blocks is maintained atlevels of at least 6%, in other embodiments at least 7%, in otherembodiments at least 8%, in other embodiments at least 9%, in otherembodiments at least 10%, in other embodiments at least 11%, and inother embodiments at least 12%. In these or other embodiments, thesolids content of the polymerization medium during formation of the Dblock is maintained at levels below 22%, in other embodiments below 20%,in other embodiments below 18%, in other embodiments below 15%, and inother embodiments below 13%. Similarly, it has been unexpectedlydiscovered that by maintaining the solids concentration of thepolymerization medium during formation of the polydiene blocks definedby d (in the formulae above) at particular concentrations, benefits arerealized in terms of an advantageous product produced at commerciallyviable rates and volumes. For example, in one or more embodiments, thesolids content of the polymerization medium during formation of the dblocks is maintained at levels of at least 0.5%, in other embodiments atleast 1%, in other embodiments at least 2%, in other embodiments atleast 3%, in other embodiments at least 4%, in other embodiments atleast 5%, and in other embodiments at least 6%. In these or otherembodiments, the solids content of the polymerization medium duringformation of the d block is maintained at levels below 8%, in otherembodiments below 7%, in other embodiments below 6%, in otherembodiments below 5%, and in other embodiments below 4%.

The polymerization can be carried out as a batch process, a continuousprocess, or a semi-continuous process. In one or more embodiments,conditions may be controlled to conduct the polymerization under apressure of from about 0.1 atmosphere to about 50 atmospheres, in otherembodiments from about 0.5 atmosphere to about 20 atmosphere, and inother embodiments from about 1 atmosphere to about 10 atmospheres. Inthese or other embodiments, the polymerization mixture may be maintainedunder anaerobic conditions.

As those skilled in the art will appreciate, the solids content of thepolymerization medium and the peak polymerization temperatures achievedduring formation of the vinyl aromatic blocks V can be adjusted toachieve maximum efficiency without impact the vinyl content of thepolydiene blocks.

In one or more embodiments, practice of the present inventionadvantageously allows for production of block copolymers attechnologically useful rates of production. For example, in one or moreembodiments, when operating at the solids contents provided for hereinfor the polydiene blocks, conversion of at least 90% of the monomer tobe polymerized is achieved within at least 8 hours, in other embodimentsat least 6 hours, in other embodiments at least 5, in other embodimentsat least 4 hours, and in other embodiments at least 3 hours. In one ormore embodiments, an overall conversion of monomer is achieved attechnologically useful levels; for example, conversions of at least 90%,in other embodiments at least 92%, in other embodiments at least 95%, inother embodiments at least 97%, and in other embodiments at least 99% ofthe monomer charged is achieved when operating at the conditionsprovided for herein.

In one or more embodiments, a quenching agent can be added to thepolymerization mixture in order to inactivate residual living polymerchains. The quenching agent may include a protic compound, whichincludes, but is not limited to, an alcohol, a carboxylic acid, aninorganic acid, water, or a mixture thereof. An antioxidant may be addedalong with, before, or after the addition of the quenching agent. Theamount of the antioxidant employed may be in the range of, for example,0.2% to 1% by weight of the polymer product. In one or more embodiments,a functionalizing or coupling agent may be used in lieu of or togetherwith a quenching agent. As those skilled in the art appreciate,functionalizing agents provide a functional group at the end of thepolymer chain, while coupling agents join two or more polymer chainstogether.

When the polymerization mixture has been quenched, the polymer productcan be recovered from the polymerization mixture by using anyconventional procedures of desolventization and drying that are known inthe art. For instance, the polymer can be recovered by subjecting thepolymer cement to steam desolventization, followed by drying theresulting polymer crumbs in a hot air tunnel. Alternatively, the polymermay be recovered by directly drying the polymer cement. The content ofthe volatile substances in the dried polymer can be below 1%, and inother embodiments below 0.5% by weight of the polymer.

For purposes of handling and transportation, the polymers of the presentinvention can be oil extended and optionally formed into bales ofpolymer. Any processing or extender oil employed in the rubber orthermoplastics industry can be employed in practicing the presentinvention. In particular embodiments, mineral oils are employed. Inother embodiments, synthetic oils, such as polybutene or polyisobutyleneoil can be employed.

The present invention will be described in more detail with reference tothe following examples. While certain of the examples illustrate the useof polymers with at least one polyvinyl aromatic segment and at leastone polydiene segment, where the polydiene segment is characterized by arelatively high vinyl content, to prepare diblock or triblock copolymersfor example, it is specifically contemplated that such polymers can beused to prepare other copolymers comprising two or more homopolymers aswell.

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXAMPLES Example 1: High Vinyl Butadiene/Styrene Diblock Copolymer

A 100 gallon reactor vessel, under a nitrogen atmosphere, was cooledwith a surrounding jacket flowing with chilled water to target atemperature between 10° C. and 20° C. The vessel was charged first withhexane and then with a 1,3-butadiene (1,3-Bd)/hexane blend (22% 1,3-Bdin solution) further referred to as Blend B. With the batch temperatureequilibrated at a target temperature between 10° C. and 20° C., thebatch was then catalyzed by charging n-butyl lithium (nBuLi) 3% solutionin hexane and immediately thereafter charging with neat oligomericoxolanyl propanes (OOPs). The vessel was then allowed to warm up for atime between 10 and 20 minutes until peak polymerization temperature wasreached and then polymerized further for a time between 10 and 15minutes to convert all 1,3-Bd to polymer.

The next block was initiated by charging the reactor vessel with astyrene/hexane blend (32% styrene in solution) further referred to asBlend S. The surrounding jacket was used to heat the reactor vessel to atemperature up to 60° C. to fully convert all monomer. The conversion ofmonomer required a polymerization time of only between 5 and 10 minutes.The reaction was terminated with neat 2-ethyl hexanoic acid (EHA). Theresulting polymer cement was dried to a crumb form.

To further illustrate the preparation of the polymer, the quantitiesused to charge the vessel in preparation of representative Sample 10 ofTable 1 are detailed as follows:

Hexane 118.3 kg Blend B  33.1 kg nBuLi (3%)  0.67 kg OOPs 0.084 kg BlendS  19.3 kg EHA 0.044 kgOther samples were prepared similarly, charging the vessel with specificamounts to generate the solids contents achieved for Samples 1 through16 in Table 1.

The resulting polymer represented by Samples 1 through 16 of Table 1 hadan average vinyl content of 80.3%. The average vinyl content for samplesin which the peak polymerization temperature of the Bd block did notexceed 46° C., i.e. Samples 1, 9-11, and 16, was 82.5%. Polymermolecular weight values were obtained from a calibrated Gel PermeationChromatography (GPC) instrument and bound styrene content and totalvinyl contents were obtained by Nuclear Magnetic Resonance (NMR) unlessotherwise noted.

TABLE 1 Peak Temp ° C. 2 Sample OOPs % Total % solids (Bd M_(p) % Bound% vinyl No. eq per Li Solids Bd block) (kg/mol) Styrene Bd 1 1 14 9.539.4 62 44.9 82.5 2 1.5 14 9.5 52.8 61 46.2 80.7 3 1.5 14 9.5 52.8 4544.2 79.8 4 1.5 14 9.5 55.6 36 44.3 78.2 5 1.5 12 7.8 63.3 59 45.0 75.36 1.5 12 7.8 50.0 44 44.8 79.9 7 1.5 10 6.4 47.2 36 43.8 79.7 8 1.5 106.4 50.6 65 44.6 81.3 9 1.5 10 6.4 38.3 44 44.7 81.6 10 1.5 8 4.9 41.145 47.2 82.1 11 1.5 8 4.9 40.6 46 46.9 82.8 12 1.5 14 9.4 50.0 75 45.378.2 13 1.5 14 9.4 55.0 90 45.0 78.4 14 1.5 14 9.4 51.1 116 46.8 81.6 151.5 14 9.4 50.0 129 45.6 78.9 16 1.5 8 6.7 35.0 99 25.1 83.4Peak polymerization temperatures of the Bd block between 46 and 55° C.may or may not yield desired high vinyl content above 80% due todependence upon multiple thermodynamic and kinetic factors. Peakpolymerization temperatures above 55° C. are not desired.

Example 2: High Vinyl butadiene/Styrene/Butadiene

A 100 gallon reactor vessel, under a nitrogen atmosphere, was cooled toa target temperature between 10° C. and 20° C. The vessel was chargedwith hexane and then with Blend B. After equilibriating to batchtemperature between 10° C. and 20° C., the polymerization was catalyzedby charging nBuLi (3% solution) and immediately thereafter charging withneat OOPS. The polymerization solution slowly exothermed over 10 to 20minutes until peak polymerization temperature was reached and thenallowed to react further for a time between 10 and 15 minutes to convertall 1,3-Bd to polymer. The next block was initiated by charging thereactor vessel with Blend S. The surrounding jacket was not heatedduring polymerization of this block.

The temperature was allowed to drop to below 30° C. before continuingwith the next block. The vessel was then charged with Blend B to formthe second high vinyl butadiene block and peak polymerizationtemperatures recorded. The reaction was terminated with neat EHA asabove in Example 1. The resulting polymer cement was dried to a crumbform.

To further illustrate the preparation of the polymer, the quantitiesused to charge the vessel in preparation of representative Sample 18 ofTable 2 are detailed as follows:

Hexane 97.1 kg 1^(st) Blend B  9.8 kg nBuLi (3%) 0.77 kg OOPs  0.1 kgBlend S 30.8 kg 2^(nd) Blend B 43.2 kg EHA 0.05 kgOther samples were prepared similarly, charging the vessel with specificamounts to generate the solids contents achieved for Samples 17 through20 of Table 2.

The resulting polymer represented by Samples 17 through 20 of Table 2had an average vinyl content of 82.0%. Polymer molecular weight valueswere obtained by GPC and bound styrene content and total vinyl contentswere obtained by NMR unless otherwise noted.

TABLE 2 Peak Temp ° C. Sample OOPs % Total % solids (Bd2 M_(p) % Bound %vinyl No. eq per Li Solids Bd1/Bd2 block) (kg/mol) Styrene Bd 17 1.5 122.0/5.2 27.8 42 45.8 81.4 18 1.5 12 2.0/5.3 39.4 62 45.9 80.5 19 1.5 122.0/5.2 26.1 76 48.3 83.9 20 1.5 12 2.0/5.3 29.4 99 46.5 82.0

Example 3: High Vinyl butadiene/Styrene/Butadiene/Styrene

A 100 gallon reactor vessel, under a nitrogen atmosphere, was cooled toa target temperature between 10° C. and 20° C. The vessel was chargedwith hexane and then with Blend B. With the batch temperatureequilibrated at a target temperature between 10° C. and 20° C., thebatch was then catalyzed by charging nBuLi (3% solution) and immediatelythereafter charging with neat OOPS. The vessel was then allowed to warmup for a time between 10 and 20 minutes until peak polymerizationtemperature was reached and then polymerized further for a time between10 and 15 minutes to convert all 1,3-Bd to polymer. The next block wasinitiated by charging the reactor vessel with Blend S. The surroundingjacket was not heated during polymerization of this block.

The temperature was allowed to drop to below 30° C. before continuingwith the next block. The vessel was then charged with Blend B to formthe second high vinyl butadiene block and peak polymerizationtemperatures recorded. The reactor vessel was further charged with BlendS. The surrounding jacket was used to heat the reactor vessel to atemperature up to 60° C. to fully convert all monomer. The conversion ofmonomer required a polymerization time of only between 5 and 10 minutes.The reaction was terminated with neat EHA. The resulting polymer cementwas dried to a crumb form.

To further illustrate the preparation of the polymer, the quantitiesused to charge the vessel in preparation of representative Sample 26 ofTable 3 are detailed as follows:

Hexane 69.2 kg 1^(st) Blend B 13.2 kg nBuLi (3%) 1.03 kg OOPs 0.134 kg 1^(st) Blend S 20.6 kg 2^(nd) Blend B 57.8 kg 2^(nd) Blend S 20.6 kg EHA0.07 kgOther samples were prepared similarly, charging the vessel with specificamounts to generate the solids contents achieved for Samples 21 through33 of Table 3.

The resulting polymer represented by Samples 21 through 33 of Table 3had an average vinyl content of 83.2%. The average vinyl content forsamples in which the peak polymerization temperature of the Bd block didnot exceed 46° C., i.e. Samples 21, 23, and 25-33, was 83.9%. Polymermolecular weight values were obtained by GPC and bound styrene contentand total vinyl contents were obtained by NMR unless otherwise noted.

TABLE 3 Peak Temp ° C. Sample OOPs % Total % solids (Bd2 M_(p) % Bound %vinyl No. eq per Li Solids Bd1/Bd2 block) (kg/mol) Styrene Bd 21 1.5 142.7/6.8 44.4 60 46.0 84.0 22 1.5 18 4.7/9.0 50.0 60 43.6 80.0 23 1.5 122.0/5.7 32.8 61 44.7 84.0 24 1.5 20  6.3/10.2 55.0 61 45.1 79.3 25 216.5 3.1/8.8 25.6 64 44.1 84.2 26 1.5 16 3.4/7.6 42.2 64 43.7 81.4 27 116.5 3.1/8.8 27.2 65 44.0 84.3 28 1.5 16.5 3.9/8.4 41.1 65 43.1 84.0 290.75 16.5 3.1/8.9 25.6 66 44.8 85.4 30 1.75 18 4.7/9.0 37.2 67 45.0 83.831 1 16.5 3.1/8.8 25.0 70 43.7 85.2 32 1.5 14 2.7/6.8 30.6 95 45.8 82.333 1.5 14 2.7/6.8 23.9 114 45.1 84.0Comparative Showing

Samples 34-36 were prepared similarly as in Example 3 charging thevessel with specific amounts to obtain the solids contents as listed onTable 4. For each Sample 34 through 36, the peak polymerizationtemperature far exceeded 46° C., the temperature below which desiredvinyl contents are confidently achieved. The peak polymerizationtemperature further exceeded 55° C., the temperature above which vinylcontent greater than 80% is not achieved.

TABLE 4 Peak Temp ° C. Sample OOPs % Total % solids (Bd2 M_(p) % Bound %vinyl No. eq per Li Solids Bd1/Bd2 block) (kg/mol) Styrene Bd 34 1 184.3/10.4 61.7 71 40.0 76 35 2 18 4.3/10.4 63.3 73 40.0  78* 36 2 184.3/10.4 62.8 71 40.0 78 *Estimated value based upon IR data.

Whereby solids content and peak polymerization temperature are wellcontrolled, the polymer and process of the invention yields desired highvinyl content block copolymers.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

The invention claimed is:
 1. A block copolymer defined by the formulaIV:d-V^(O)-D-V′-ω  (IV) where V^(O) and V′ are each independently apolyvinyl aromatic block, d and D are each independently a polydieneblock, ω is a hydrogen atom, a functional group, or a polymeric segmentor block, where d is characterized by a vinyl content of at least 80%,and where d includes less than 160 mer units.
 2. The block copolymer ofclaim 1, where the vinyl content of the block copolymer is at least 80%.3. The block copolymer of claim 1, where d is characterized by a vinylcontent of at least 85%.
 4. The block copolymer of claim 1, where eachpolyvinyl aromatic block derives from the polymerization of vinylaromatic monomer selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, and vinylnaphthalene.
 5. The block copolymerof claim 4, where the vinyl aromatic monomer is styrene.
 6. The blockcopolymer of claim 1, where V^(O) includes at least 25 and less than 200mer units, D includes at least 250 and less than 800 mer units, and V′includes at least 25 and less than 200 mer units.
 7. The block copolymerof claim 1, where d includes less than 120 mer units.
 8. The blockcopolymer of claim 1, where d derives from the polymerization of1,3-butadiene.
 9. A block copolymer defined by the formula IV:d-V^(O)-D-V′-ω  (IV) where V^(O) and V′ are each independently apolyvinyl aromatic block, d and D are each independently a polydieneblock, ω is a hydrogen atom, a functional group, or a polymeric segmentor block, where d derives from the polymerization of 1,3-butadiene andis characterized by a vinyl content of at least 85%, and where dincludes less than 120 mer units, where the vinyl content of the blockcopolymer is at least 80%.
 10. The block copolymer of claim 9, whereeach polyvinyl aromatic block derives from the polymerization of vinylaromatic monomer selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, and vinylnaphthalene.
 11. The block copolymerof claim 10, where the vinyl aromatic monomer is styrene.
 12. A blockcopolymer defined by the formula IV:d-V^(O)-D-V′-ω  (IV) where V^(O) and V′ are each independently apolyvinyl aromatic block deriving from the polymerization of styrene, dand D are each independently a polydiene block deriving from thepolymerization of 1,3-butadiene, ω is a hydrogen atom, a functionalgroup, or a polymeric segment or block, where d is characterized by avinyl content of at least 80%, and where d includes less than 160 merunits.
 13. The block copolymer of claim 12, where the vinyl content ofthe block copolymer is at least 80%.
 14. The block copolymer of claim13, where d is characterized by a vinyl content of at least 85%.
 15. Theblock copolymer of claim 14, where d includes less than 120 mer units.